Indoor Packaged Remote Air-Cooled Unit
Constant Volume Application
HVAC Guide Specifications
Size Range: 5 to 20 Tons
Carrier Model Number: 50XCR
Part 1—General
1.01 SYSTEM DESCRIPTION
Indoor packaged vertical air-cooled cooling unit using hermetic scroll compressors for cooling duty. Unit shall discharge supply air vertically or horizontally (sizes 12-24) as shown on contract drawings.
1.02 QUALITY ASSURANCE
A. Units shall be rated in accordance with AHRI (Air-Conditioning, Heating and Refrigeration Institute) Standard 340/360, latest revision, as appropriate.
B. Unit shall be designed to conform to ANSI/ASHRAE (American National Standards Institute/American Society of Heating, Refrigerating and Air-Conditioning Engineers) 15, latest revision safety code.
C. Units 06-24 (5-20 tons) shall be designed to meet or exceed ASHRAE 90.1-2016 (American Society of Heating, Refrigerating, and Air-Conditioning Engineers) and DOE-2018 (Department of Energy) minimum efficiency ratios.
D. The management system governing the manufacture of this product is ISO 2001:2008 certified.
E. Insulation, adhesive, and liner system shall meet NFPA (National Fire Protection Association) 90A requirements for flame spread and smoke generation.
F. Unit shall be ETL and ETL, Canada certified.
1.03 DELIVERY, STORAGE, AND HANDLING
Units shall be stored and handled according to manufacturer’s recommendations.
Part 2—Products
2.01 EQUIPMENT
A. General:
Factory-assembled, single-piece, air-cooled cooling unit. Unit shall consist of scroll refrigerant compressor(s), evaporator fan section with belt drive centrifugal fans and motor, evaporator coil section with direct expansion coil and drain pan, and a system charge of refrigerant (R-410A). Unit may be used with or without return ductwork.
B. Unit Cabinet:
1. Cabinet shall be constructed of minimum 18 gage zinc surface alloyed steel with a baked enamel finish. Unit shall be capable of withstanding ASTM (American Society for Testing and Materials) B117 500-hour salt spray test.
2. Cabinet shall be fully insulated.
3. Configurations include vertical or horizontal discharge with a ducted or louvered return.
4. Unit drain pan shall be stainless steel and shall have positive double slope to the drain to prevent standing water in pan.
5. Panels for servicing shall be easily removable.
C. Evaporator Fan Section:
1. Fans shall be double inlet, centrifugal wheel with forward curved blades designed for continuous operation. Fan wheel and scroll shall be constructed of steel with corrosion resistant finish, and statically and dynamically balanced.
2. Fan shall be belt drive with an adjustable pitch motor pulley and fixed pitch fan pulley, with permanently lubricated ball-bearing typebearings.
3. Motor shall be 3-phase high-efficiency NEMA (National Electrical Manufacturing Association) frame ODP (open drip proof) of the same voltage as the compressor(s). Motor shall have permanently lubricated ball bearings.
4. Fan section may be equipped with a variable frequency drive for dual-stage units to operate at 67% of full speed for first stage cooling and 100% of full speed for second stage cooling.
D. Compressor:
Hermetic scroll compressors shall be internally protected with high pressure relief. Compressors shall be factory mounted with vibration isolators.
E. Coils:
1. Evaporator coil shall have aluminum plate fins mechanically bonded to seamless copper tubes with all joints brazed. Tube sheet openings shall be swaged to prevent tube wear. Coils shall be full face.
2. Direct expansion coil shall be designed and tested in accordance with ANSI/ASHRAE 15, latest revision safety code.
3. Coil and drain pan shall be accessible through service access panels for cleaning.
F. Filter:
Filter frame shall be installed upstream of the cooling coil, designed to take a 1-in. or 2-in. thick disposable type commercially available filter. Filters shall be accessible from either side of the unit and filter rack shall be usable with ducted or free return. Disposable filters will be supplied with the unit. 4-in. filter racks are available.
G. Operating Characteristics:
Unit shall be capable of providing a constant volume of conditioned air at a specified static pressure within the unit’s normal operating range. Unit shall have dual-stage cooling capacity control on all units. Sizes 06 and 08 have one compressor, with two stages. Sizes 12 through 24 have two compressors in tandem on a single circuit. Unit shall be capable of starting and operating at up to 115°F outdoor ambient.
H.Controls and Safeties:
1. Units shall be furnished with a control terminal block for connection of thermostats.
2. Unit shall require a room-mounted thermostat to be mounted in the conditioned space. Thermostat shall be digital type. Thermostat shall control fan operation and be capable of turning unit on and off.
3. Units shall have the following factory-installed safeties: high and low-pressure switches, motor and compressor overtemperature, current lockout, and inherent automatic fan motor overload.
I. Electrical Requirements:
All electrical power wiring shall enter the unit cabinet at a single location. Control circuit shall be 24-v, suitable for a field-supplied 24-v thermostat.
J. Refrigerant Components:
Refrigerant circuit components shall include thermal expansion valves, distributor with nozzle, filter driers, and charging service valves on each circuit. Suction line shall have a refrigerant loop to prevent refrigerant drain back to the compressor. Suction piping shall be insulated with closed cell pipinginsulation.
K. Special Features:
1. Air Discharge Plenum:
Plenum shall be provided to permit free-blow horizontal air distribution with movable vanes to adjust airflow in horizontal and vertical direction. Plenum is field installed and shall be fully insulated.
2. Heating Coil:
Field-installed hot water coil shall be two rows with copper tube aluminum fins and a powder coated steel casing. Fins shall be bonded to tubes by mechanical expansion. Coil to be leak tested at 400 psig air pressure submerged in water and charged with dry air.
3. Thermostats:
A complete line of thermostats shall be available to meet any application control requirements.
4. Steam coil:
Field-installed steam heating coil shall be of a steam distributing tube type, aluminum fin coil to be mounted external to the unit.
5. Evaporator coil coating:
The coating shall be continuous and cover the whole fin surface, tubing, manifolds, and feeder lines if applicable. For evaporator coils with thermostatic expansion valve assemblies, valve body, head, and bulb shall be masked. A minimum of 2-inches shall be masked on all coil connection points. For expansion valve inlet piping if less than 6-inches in total length, expansion valve distributor, and external equalizer line are not required to be coated.
6. Winter start kit:
Will provide a bypass of low pressure switch on start-up for initial 90 seconds.
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